Micro-electromechanical systems, or MEMS, is a technology that integrates miniaturized mechanical and electro-mechanical elements on an integrated chip. MEMS devices are often made using micro-fabrication techniques. In recent years, MEMS devices have found a wide range of applications. For example, MEMS devices are found in cell phones (e.g., accelerometers, gyroscopes, digital compasses), pressure sensors, micro-fluidic elements (e.g., valves, pumps), optical switches (e.g., mirrors), etc.